Audio Drift

Peter C.

Peter C.

Veteran
Has there been any advancement in software that fixes audio drift?

Unfortunately I don't have equipment/time/money to have build a time code based system and I'm doing lower end event work not movies. I'll often have multiple cameras and audio recorders and over a 1-2 hour performance drift becomes an issue. It's a time consuming process to manually play with the speed of the audio tracks to get them align.
 
I thought this was a done deal on modern editing software. Certainly Davinci Resolve can auto-align tracks if you have a scratch track on the camera. I haven't used it as I use timecode. I suggest seriously considering investing in Tentacle Syncs. They are so easy to use and everything is in sync. Easy peasy.

It's a big plus to have the timecode when editing. You will save yourself piles of time.
 
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Paul F said:
I thought this was a done deal on modern editing software. Certainly Davinci Resolve can auto-align tracks if you have a scratch track on the camera. I haven't used it as I use timecode. I suggest seriously considering investing in Tentacle Syncs. They are so easy to use and everything is in sync. Easy peasy.

It's a big plus to have the timecode when editing. You will save yourself piles of time.
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My video editing software has built in audio sync but that doesn't fix drift. It starts in sync but slowly drifts developing an echo as the performance progresses.

I'm using a Zoom f3 32bit recorder that supplies phantom power to two stage mics. The F3 has no internal timecode I believe you have buy a Ultrasync BLUE for timecode jam sync. I'm also 65 feet away form the recorder so not sure Ultrasync that uses bluetooth could reach that far.
 
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SMPTE Timecode alone will not prevent or resolve A/V drift. Genlock devices will keep multiple cams and audio recorders at the exact same speed There is software available like PluralEyes to resolve it in post or it can be done manually , which can be labor intensive if there are many clips.
 
Peter C. said:
My video editing software has built in audio sync but that doesn't fix drift. It starts in sync but slowly drifts developing an echo as the performance progresses.
.
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Yes, but why not re-sync each edit?

Peter C. said:
I'm using aZoom f3 32bit recorder that supplies phantom power to two stage mics. The F3 has no internal timecode I believe you have buy a Ultrasync BLUE for timecode jam sync. I'm also 65 feet away form the recorder so not sure Ultrasync that uses bluetooth could reach that far.
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You can use any timecode device at the F3 and at your cameras. For the Tentacle, bluetooth is used to set up and monitor, but it is not required to operate. The devices will drift less than a frame in 24 hours without the master being in contact with the other units. One person tested the app and found it to have a range of over 100m.
 
I looked at the Ultrasync price is as follows:
$40 bluetooth adapter for the F3
$150 Ultrasync Blue
$279 Ultrasync One
Total $469 and an additional $279 for each additional camera. In my case $748

Matt has a video on it.
 
Echh. Why Ultrasync? It's from a company that is well..... let's say..... having difficulty? Will they be around tomorrow? Plus really expensive, proprietary connectors/cables.

Tentacle Sync E - $200 each. No adapters required. No special cables. Tiny.
 
I'm not talking about genlock. I'm talking about timecode sync.

One tentacle on each camera.
One tentacle on each audio recorder.
Pre-show, sync all Tentacles
Done
Standard 3.5mm connector to BNC or ?
 
Paul, I just want to check that you are solely thinking about audio drift. Many audio recorders do not have their recording crystals open to be controlled by outside devices. High end ones, yes. It is a problem because a 2 hour event IS the edit. No chance to realign a clip so to speak.

Peter, if you do get this job on a timeline, I think the best way to fix drift is to go every 10-20 min of your timeline and just slide the offending clips at the sample level (or frame level if that is not too much). The pitch change software was not good enough in my opinion.
 
Yea, I guess maybe there is something I'm missing.

I get it. The picture and audio are drifting. I'm not considering that the recorder has a genlock. But all recorders can record timecode even if they don't have a timecode input. If someone is doing a show with a separate audio mixer, it should have a timecode input. But it's not necessary.

Since this is a multicam shoot, I assume the picture is cut from camera to camera every so often. So while the audio is not cut (one single take), the picture is. So any drift might be a fraction of a frame over time, but really not noticeable in the edit since the timecode will be frame accurate to the audio track.

Maybe I don't understand. I guess there is a hint in that Peter says there is an echo. Where is that coming from? Isn't this all one audio recording? Is the audio being recorded on multiple cameras and that is the audio that is being used? Uggh, that would be a problem.
 
Sorry I'm a little confused how the Tentacle Sync E works especially with the Zoom F3. Tentacle generates time code but how does that go in to the F3 the F3 has no internal timecode or way to input it.

Filming stage performance in particular there are sometimes multiple audio inputs
1. Shotgun mic on camera
2. Feed from the sound board into camera
3. Boundary mics the stage.

Audio gets mixed together, but if the audio recorder, and the cameras are recording the audio and different speed they begin to drift apart. Depending on how big the dependency between the devices they will drift out of sync.

I also know how to manually fix it in post I was asking if there was a utility the would do this automatically.
 
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I misunderstood what you are doing. No wonder you have problems. I suggest re-thinking your production process. Audio needs to be recorded to one recording device otherwise, you are just beating yourself up with problems.
 
Yes. The semantics are "drift" and "sync". Drift is two or more audio tracks recording at slightly different speeds which becomes audible over a certain amount of time. Sync is more about starting together but 'keeping sync' is timecode, genlock or word clock etc...

Paul is right, maybe run longer cables to record into one device if it has enough inputs or mix it in a mixing board before recording. I have not come across anything that fixes drift and keeps true audio fidelity. The F3 is the issue but it is a nice unit. I have the F6 but it has timecode in which helps :(
 
It's 65 feet from the camera to the stage. I can send the signal back to the camera using a wireless unit but turns the mics into a mono feed. I discovered my JVC camcorders have a TC in/out but my Panasonic don't. It opens a can of worms that I'd rather fix it in post than spend the money and deal with the complexity. Only a few performances I use stage mics the more professional schools they mic everything up proper and can rely on a the board feed going directly to camera.
 
Peter C. said:
Has there been any advancement in software that fixes audio drift?

Unfortunately I don't have equipment/time/money to have build a time code based system and I'm doing lower end event work not movies. I'll often have multiple cameras and audio recorders and over a 1-2 hour performance drift becomes an issue. It's a time consuming process to manually play with the speed of the audio tracks to get them align.
Click to expand...

My ten cents. I don't know what NLE you are using but in Resolve "Elastic Waveform" is fast, easy and accurate for long contiguous clip audio sync jobs. For complex multiple stop / start unlinked non synced multi cam camera files that need syncing with standalone recorders, I use Syncaila or Pluraleyes. Both have their strengths and weaknesses. Both require a timeline XML export and then a re-import of a synced XML to work. For very bad drift problems, Pluraleyes still seems the most accurate with its very good "drift correction" process that takes place after it has synced all clips. Pluraleyes is no longer produced but can still be purchased for a few more months and there will be no more ongoing support or upgrades, but seriously that is not an issue as far as I'm concerned.

Chris Young



 
I was using FCPX and did a similar thing by changing the speed duration but it's annoying. It wasn't allowing me to do small duration changes. I ended up stretching the speed manually in the timeline and it worked.

I'll look into the Pluraleyes.

Btw found 9 year old Curtis Judd video and Audition has a feature just for this

I'm making more a fuss then in warranted. I only film a handful of performances that use an external recorder. Every few years I revisit it.
 
One way to look at it as if the budget is low, then the output might have to be lower than usual. I know that is tough and I never want to release anything that is not top quality, but sometimes reality is reality. I have found cutting in a dead spot and sliding to be not that difficult once the general time frame for the drift is discovered. Low tech but you control the output quality.
 
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